1. Field of the Invention
This invention relates to vehicle display systems, and particularly to a vehicle display system comprising a plurality of display units having a receiver for receiving measured data indicating a state of the vehicle and a driver controller for controlling an indicator driver for driving an indicator according to the measured data, and a controller unit having a transmitter for transmitting the measured data to the display units and a transmitter controller for controlling the transmitter.
2. Description of the Related Art
Generally, a vehicle display system provided in an interior of the vehicle is arranged in an instrument panel in front of a driver's seat in order that the driver sitting on the driver's seat can visually recognize respective display units of meter devices through a steering wheel. This vehicle display system includes a plurality of display areas for displaying vehicle speed, rotations per minute of a rotating shaft, fuel level, cooling water temperature gauge, and the like of the vehicle. These display areas are arranged efficiently in a same container in order that the driver can recognize a state of the vehicle at a glance.
FIG. 10 is a perspective view showing a conventional vehicle display system, and FIG. 11 is a cross-sectional view taken on line A—A of FIG. 10.
A conventional vehicle display system comprises: a display unit board 1 on which a circuit pattern (not shown) is formed to connect a front surface 1a with a back surface 1b of the display unit board 1 electrically; and display units assembled on the front surface 1a of the display unit board 1 respectively, such as a speedometer 2 for indicating the vehicle speed, a tachometer 5 for indicating rotations per minute of a rotating shaft, a fuel gauge 8 for indicating the fuel level, and a thermometer 11 for indicating a temperature of the vehicle interior.
The speedometer 2 is composed of a stepper motor 3 fixed on the display unit board 1 and a pointer 4 attached to an output axis 3a of the stepper motor 3. The stepper motor 3 works as an inner mechanism for driving the pointer 4 according to the measured data of the vehicle speed.
The tachometer 5 is composed of a stepper motor 6 fixed on the display unit board 1 and a pointer 7 attached to an output axis 6a of the stepper motor 6. The stepper motor 6 works as an inner mechanism for driving the pointer 7 according to the measured data of the rotations per minute of the rotating shaft of the vehicle.
The fuel gauge 8 is composed of a stepper motor 9 fixed on the display unit board 1 and a pointer 10 attached to an output axis 9a of the stepper motor 9. The stepper motor 9 works as an inner mechanism for driving the pointer 10 according to the measured data of the amount of the fuel of the vehicle.
The thermometer 11 is composed of a stepper motor 12 fixed on the display unit board 1 and a pointer 13 attached to an output axis 12a of the stepper motor 12. The stepper motor 12 works as an inner mechanism for driving the pointer 13 according to the measured data of the temperature of the vehicle interior.
A dial plate (not shown) having indexes such as graduations and numbers, letters or marks thereon in order to achieve each meter function is arranged in between each stepper motor and indicator which are components of each meter equipment.
Moreover, the vehicle display system comprises: an infrared light receiving element 14 and a stepping motor driver cum infrared communication IC 15 connected electrically to a speedometer 2 mounted on a front surface 1a; an infrared light receiving element 16 and a stepping motor driver cum infrared communication IC 17 connected electrically to the tachometer 5 mounted on the front surface 1a; an infrared light receiving element 18 and a stepping motor driver cum infrared communication IC 19 connected electrically to the fuel gauge 8 mounted on the front surface 1a; and an infrared light receiving element 20 and a stepping motor driver cum infrared communication IC 21 connected electrically to the thermometer 11 mounted on the front surface 1a. Each infrared light receiving element and stepping motor driver cum infrared communication IC are mounted on the back surface 1b of the display unit board 1.
Further, the vehicle display system includes a control module 22 attached to the back surface 1b of the display unit board 1. This control module 22 has a circuit board with a circuit pattern (not shown) which ICs 24 and a infrared light emitting element 25 are mounted on and connected electrically to through the circuit pattern respectively. Said ICs 24 include an interface (I/F) integrated circuit (IC) and a microcomputer IC.
The control module 22 is detachably attached to the display unit board 1 by two attachments 23. Each attachment 23 has a groove 23a for fitting a board of the control module 22 into one end thereof and two claw-like engaging portions 23b at the other end thereof for engaging the control module 22 resiliently with engaging holes of the display unit board 1.
Each data of vehicle speed, rotations per minute of a rotating shaft, fuel level, and temperature of the vehicle interior measured by various sensors (not shown) is inputted into the control module 22 in such as a serial data format. Then, the measured data is processed according to the inputted data to be assigned a specific identification code respectively and is transmitted as an infrared signal from the infrared light emitting element 25.
The infrared signal transmitted from the infrared light emitting element 25 is received by respective infrared receiving elements 14, 16, 18 and 20 to be supplied to respective stepping motor driver cum infrared communication ICs 15, 17, 19 and 21. Respective Stepping motor driver cum infrared communication ICs 15, 17, 19 and 21 supply respectively the vehicle speed data, the rotations per minute of a rotating shaft data, the fuel level data or the temperature of the vehicle interior selectively according to the specific identification code for each meter, namely, the speedometer 2, the tachometer 5, the fuel gauge 8 or the thermometer 11.
In this manner, a control portion, which is the basic functional portion for controlling the various meters for indicating the measured data of the state of the vehicle, is modularized into the control module 22 to be adapted to every meter. The output from the control module 22 is an infrared communication signal. Each pair of the infrared receiving element and the mating stepping motor driver cum infrared communication IC is mounted in the display unit board 1.
Each of stepper motors 3, 6, 9 and 12 which is a component of an indicator such as the speedometer 2, the tachometer 5, the fuel gauge 8, the thermometer 11 or the like is connected with each of stepping motor driver cum infrared communication ICs 15, 17, 19 and 21, so that said each of stepper motors 3, 6, 9 and 12 is controlled by the infrared signal from the control module 22.
However, in a case that a communication of the control module 22 is limited to the transmission, the control module 22 keeps transmitting data even if some communication trouble occurs. Therefore, if the control module 22 transmits a large amount of data at the time when the communication returns to normal, a probability of stepping out of the stepper motors 3, 6, 9, and 12 becomes high. The control module 22 has to take measures against said stepping out. Resultingly, there is a problem that the display control becomes complicated in this manner.